Ceiling Function is the least integer that is greater than or equal to x.
Answer:
Option 3 is correct that is 
Step-by-step explanation:
We have general formula for sum of cube which is

Here, we have a=s and b=6
on substituting the values in the formula we will get

After simplification we will get

After rearranging the terms we will get
which exactly matches option 3 in the given options.
Therefore, option 3 is correct that is 
Because 3/6 is equal to 1/2 (one half).
Answer:
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Step-by-step explanation:
After 40 minutes, Ralph has already painted (40/60)/12=1/18 of the fence
Lisa's speed is 1/15 fence/hour, Ralph's speed is 1/12 fence/hour, hence when they help each other their combined speed is 1/15+1/12=3/20
Thus we need to solve 3/20*x=17/18 thus x=170/27 hours (approx 6 hours 15 mins)